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Software Support => GroovyMAME => Topic started by: quartex73 on April 30, 2021, 06:55:39 pm

Title: Newbie problem with a crt tv 15khz
Post by: quartex73 on April 30, 2021, 06:55:39 pm
Hi all.
I'm using an amd radeon 6310.
My previous setup using a vga crt pc monitor 31khz works fine (tried both groovyarcade and crtemudriver 2.0 on win7).
Now I got a crt tv 15khz United utv2014x (pal with an euroscart rgb) and the "arcade ultimate vga to scart 15.7khz cable pc.
New win7, installed crtemudriver 2.0 and set monitor type arcade 15.7 (tried also generic 15.7, pal and ntsc tv), enable edid emulation. Pc monitor goes out of sync and I connected  vga card to tv using the cable.  Turn on but the image is terrible.  Looks interlaced with black bars up and down.
But what worries me is that the led on the cable is red. So it looks something is wrong.  According to cable producer: "if the input signal is incorrect and is not 15.7khz the red led will light up".
Any help would be really appreciated.  Thanks
Title: Re: Newbie problem with a crt tv 15khz
Post by: quartex73 on April 30, 2021, 07:01:35 pm
Attachment
Title: Re: Newbie problem with a crt tv 15khz
Post by: Zebidee on May 01, 2021, 08:16:46 am
CRTEMU seems right.

Looks a lot like signal interference. If the TV is otherwise able to show an image OK, then it is probably the cable causing the issue. Open it up and have a look inside? Maybe something is shorting.

If you can solder, you can also make your own easy enough in a few hours, and output composite sync from crt_emudriver.
Title: Re: Newbie problem with a crt tv 15khz
Post by: quartex73 on May 01, 2021, 02:37:35 pm
I noticed led is green at boot then become red when windows is loaded even with scart disconnected from tv.  Does this rule out tv issue? Could be a problem related to graphic card? (Integrated amd radeon hd 6310 on a e-350 mobo). At 31khz works fine  (with a pc crt vga 31khz monitor)
Title: Re: Newbie problem with a crt tv 15khz
Post by: Zebidee on May 01, 2021, 06:04:16 pm
Just re-read your first post. Did you regenerate and reinstall the video modes after clicking to enable EDID?
Title: Re: Newbie problem with a crt tv 15khz
Post by: quartex73 on May 01, 2021, 06:54:19 pm
Just re-read your first post. Did you regenerate and reinstall the video modes after clicking to enable EDID?

Yes, I did it everytime for each profile (arcade, generic arcade, pal, ntsc).  For security I created a restore point on win7 just before enabling EDID that I used for each try
Title: Re: Newbie problem with a crt tv 15khz
Post by: Zebidee on May 01, 2021, 07:51:43 pm
What I meant is after every time you click on EDID emulation for the CRT display, you must regenerate and reinstall the modes. In your original post you were doing the generating/installing video modes before clicking on EDID emulation.

May as well just stick to generic_15khz profile for now.

Having said all that, the black bars do look like a problem with the sync (vertical). Looks like a cable problem!

The LED colour change is normal with the gambaman PIC based composite sync. LED changing means it is 'working'. I have a VGA-VGA dongle that filters 15khz and makes csync, made by @buttersoft, that is based on the same PIC used in your cable (AFAIK). So my dongle should work the same way as your cable.

It is possible that yours is having trouble properly locking onto the sync signals from your GPU. This can happen especially if the sync voltage levels are relatively low or quite different (between H+V). To investigate further you'd need a decent multimeter, or even better an oscilloscope.

Alternatively, it is possible to make your own SCART cable, run the H+V sync through resistors (~470R to 1k, depending on sync levels) and twist together to get "smushy" sync that will work for most TVs. You'd need some soldering and stuff for that, but at least then you could get a baseline for what works and what doesn't.
Title: Re: Newbie problem with a crt tv 15khz
Post by: abispac on May 02, 2021, 10:58:10 am
try not using super resolutions.
Title: Re: Newbie problem with a crt tv 15khz
Post by: quartex73 on May 02, 2021, 02:14:23 pm
try not using super resolutions.

Already tried, didn't fix
Title: Re: Newbie problem with a crt tv 15khz
Post by: Zebidee on May 03, 2021, 01:33:44 am
Super resolutions aren't the issue. I'm 98% sure it relates to your sync, either the ultimate cable itself, or the combination/interface between your graphics card sync and the cable. You might want to talk about this with whomever supplied you with the cable.

To make sure, I suggest you get another cable or make one yourself. There is a stickied thread of how to make VGA-SCART cables on the Monitor/Video branch, but it hasn't been active for a while and some parts could be updated.

If you can't make a cable yourself and are are stuck for options, I could perhaps make one for you. I have a lot of experience making VGA-SCART cables, have made quite a few for forum members here over the past 15 years or so. Last time I made a custom SCART cable was a few months ago, for Calamity himself (summary: it works :D). PM me if interested in this option.
Title: Re: Newbie problem with a crt tv 15khz
Post by: quartex73 on May 09, 2021, 12:53:26 pm
Super resolutions aren't the issue. I'm 98% sure it relates to your sync, either the ultimate cable itself, or the combination/interface between your graphics card sync and the cable. You might want to talk about this with whomever supplied you with the cable.

To make sure, I suggest you get another cable or make one yourself. There is a stickied thread of how to make VGA-SCART cables on the Monitor/Video branch, but it hasn't been active for a while and some parts could be updated.

If you can't make a cable yourself and are are stuck for options, I could perhaps make one for you. I have a lot of experience making VGA-SCART cables, have made quite a few for forum members here over the past 15 years or so. Last time I made a custom SCART cable was a few months ago, for Calamity himself (summary: it works :D). PM me if interested in this option.


Thank you very much, really appreciated.  Just before reading your reply I ordered a new cable from another reseller, I'm waiting delivery.   Also I've tried with another gpu radeon (this time pci-e) but it didn't work so looks like it's related to cable.

Just to know (a bit out of topic), can a pc 31Khz crt monitor and a crt 15Hz tv stay close to each other? I read about magnetism and that can create permanent damages.  I noticed (when both were turned on) flickering on crt monitor
Title: Re: Newbie problem with a crt tv 15khz
Post by: Zebidee on May 09, 2021, 06:40:43 pm
CRTs have a built-in degaussing coil which surrounds the tube. It is basically a big electromagnet which is automatically activated for a second or two when you turn CRT on from a cold start (it won't happen if the CRT is warm, used recently).

The degaussing coil is to remove any colour impurities in the screen that may have been introduced from magnetic fields nearby, including the Earth's own magnetic fields.

So yes, if you have the CRTs next to each other, one on already, and turn the other on, you may see some weird ---steaming pile of meadow muffin--- going with first CRT's picture. This isn't a cause for concern as the degaussing coil is only active for a second or two. Also, even if if affects the other CRTs screen phosphors somehow, the effect will be gone next time you restart the CRT (as the screen will degauss itself).